Piano tuning wrenches



June 26, 1956 s. 1.. LEFTLY 2,751,805

PIANO TUNING WRENCHES Filed Feb. 1, 1955 Z0 Z6 m 23 6Z 26 Fg g us D 210I i' 152 zzmrwifl WWW United States Patent i PIANO TUNING WRENCHESStanley Leonard Leftly, Toronto, Ontario, Canada Application February 1,1955, Serial No. 485,539

3 Claims. (Cl. 84-459) This invention relates to piano tuning pin socketwrenches, which are generally known in the art as piano tuning hammers,and consists of a novel construction and arrangement of gears andlinkage engaging a specially constructed wrench having the ordinary wellknown eight point star socket.

An object of the present invention is to provide a readily and quicklyapplied means of precise control over manually applied force-s necessaryto regulate and adjust tension of musical strings on a pianoforte.

The above as well as additional objects will be clarified in thefollowing description wherein characters of reference refer to likenumbered parts in the accompanying drawing. It is to be noted that thedrawing is intended solely for the purpose of illustration and that itis therefore neither desired nor intended to limit the inventionnecessarily to any or all of the exact details of construction shownexcept insofar as they may be deemed essential to the invention.

Referring briefly to the drawing,

Fig. 1 is a fragmentary perspective view of a piano showing the pinblock with the tuning hammer of the present invention about to beapplied to a pin to be tuned and another pin remote therefrom.

Pig. 2 is a front elevation view of the tuning hammer.

Fig. 3 is a top plan view of the tuning hammer.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2.

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 3.

Referring in detail to the drawing, the numeral indicates the pin blockof a piano, having the tuning pins 11 mounted thereon in which the upperends of the strings 12 are anchored and by turning which, as is wellknown, the strings are tightened or loosened as desired to be properlytuned.

The apparatus of the present invention is constructed as follows. Atubular socket wrench 13 having a standard eight pointed star socket 14is adapted to be applied over and engage any of the tuning pins 11.

Rigid on the outer end of the wrench 13 is one end of a sector arm 15having at its other end an arc of internally formed gear teeth 16concentric with axis of Wrench 13.

Rigidly attached to one end of an elongated arm 17 is a stud held inpivotal engagement with the outer end of the tubular wrench 13, andhence with the sector arm 15, by a retaining pin 27.

The other end of the arm 17 is pivoted to one end of a link 18 by apivot pin 21. The other end of link 18 is pivotaliy engaged to the outerend of a sleeve 19. The link 18 is preferably formed by bifurcating oneend thereof so that the members 18a and 18b so produced engage oppositesides of the arm 17. The link 18, it is to be noted, is both slidablyand pivotally secured to the sleeve 19.

As shown in Fig. 4 of the drawing the internal diameter of the sleeve 19is reduced at the pin engaging end to 2,751,805 Patented June 26, 1956form an internal flange 22a. The sleeve is also provided at the same endwith an external flange 22, and at a point a suitable distance from theother end of the sleeve 19 a stop pin 23 is rigid with the sleeve; thelink 18 being mounted between this pin 23 and the flange 22. Acompression spring 24 surrounding the sleeve 19 between the flange 22and the link 18 normally urges the latter outward on the sleeve againstthe stop pin 23.

With the link 18 in its outer extreme position on the sleeve and withthe device applied for operation as indicated in Fig. 1, the arm 17 andthe link 18 lie in a common plane parallel to the pin block 10.

Pivoted to the arm 17 and in mesh with the internally formed gear teeth16 is a pinion 25 having an extended shaft 26 rigid therewith, thelatter having its outer end of square section exactly similar to that ofa standard tuning pin 11 so that the pinion 25 may be rotated, throughthe shaft extension 26, by means of an ordinary standard tuning hammerof the prior art or, alternatively, by any suitable key 29 as may bedesired.

Since it is desirable, in order to avoid confusion in practice, that theeffort arm of any tuning hammer be moved in the same angular directionas the pin to be tuned it is to be noted that as a result of theparticular combination of the pinion 25 and the teeth 16 of the sectorarm 15 in the present invention, an angular movement of the effort armkey 29 produces simultaneously a movement of the socket 14 in the sameangular direction without interposition of an idler or compounding gearsuch as would otherwise be required. It is also to be noted that owingto the particular construction of the sector arm 15 of the presentinvention, a direct view of pertinent pins, strings and other parts, isavailable to the user of the device while normally seated in front ofthe piano to which the device is being applied.

Assuming that a pin 11, all of which are alike and square in crosssection, is to be manipulated to change the tension on the string 12attached thereto, the device is applied as follows:

With the pinion 25 in mesh with the teeth 16 at approximately the centreof the are formed by the latter, the socket 14 is applied over theselected pin 11 in such a position that the arm 17 extends across aportion of the pin block 10 and that the link 18, and hence the sleeve19 may be swung radially about the pivot 21 in one direction or theother over one or more of the other tuning pins 11 remote from theselected pin. With the arm 17 and the link 18 angular-1y disposed eachto the other as nearly as may be as indicated in Fig. 1 of the drawing,and with the sleeve 19 pulled outwards against the spring 24 and inalignment with a remote pin 11a, upon release of the sleeve it will beforced by the spring 24 over the pin 11a so that the internal flange 22awill be positioned relatively close to the base of the pin 11a.

Since, however, because of the eight point form of its socket 14, thewrench 13 is fittable over any pin 11 only in eight circumferentialpositions and because the facets of the squared ends of all such pins 11on a piano are not uniformly orientated, the link 18 and the arm 17 areof such length that the device may be applied as described with aminimum of relative movement of the arm 17 to the sector arm 15 andhence a minimum rotation of pinion 25. The device, therefore, may bereadily and quickly applied to the appropriate pins 11 and 11a withoutregard to the orientation of the facets thereof.

The exact step by step procedure of applying the device to the tuningpins is, of course, of no consequence to the invention and some may doit one way and others in another way. The essential thing is to applythe device with the wrench on the pin to be tuned and the sleeve on asuitably positioned distant pin. It is to be noted that the device maybe applied so that a pin 11a is either on the right or on the left of apin 11 selected for tuning, as may be convenient to avoid obstructionssuch as, for instance, the side of the piano casing, frame ribs, and thelike.

With the device so mounted, turning of the pinion extension 26 by meansof a common tuning hammer or suitable key 29 will, through the pinion 25and the internaily cut teeth 16, swing the arm 15 thus turning theselected pin 11 engaged by the wrench 13 to tense or loosen the string12 thereon.

Since the linkage 17, 18 is supported at three points which, itconnected would form a triangle, that is, the axis of the pin in thesocket 14; the pivot axis between the arm 17 and the link 18; and theaxis of the remote pin limit is obvious that the linkage is rigid andimmovable. However, the linkage tends to apply a force on the pin 11::through the sleeve 19 in the nature of a moment tending to bend the pin,upon which the sleeve registers, at its base. If the sleeve 19 did nothave the reduced opening provided by the inner flange 22a, theconsequent tilting of the sleeve 19 would cause the inner wall thereofto make contact with the tip of the pin 11 11 and tend to bend it. Thiseffect is reduced to a minimum by engagement of the pin 11a with theinner flange 22a much closer to the base of the pin, and the fact thatthe c inner wall of the sleeve does not make, contact with the pin.

The remote pin 11a on which the sleeve registers serves merely to createan equilibrant force component when applying torque on the pin 11 withinthe socket 14, and owing to the engagement of the pin 11a with theflange 22a as just mentioned, the possibility of putting the string ofthe remote pin out of tune after it has previously been tuned, isminimized.

The great ratio between the pitch radii of teeth of pinion 25, andsector arm teeth 16 of course offers a mechanical advantage so that aproper torsional force is applied to the pin being tuned, with a minimumelfort on the part of the user in turning the key 29. Consequently avery precisely controlled variation of tension of the relevant string 12is possible to ensure a fine degree of tuning.

Obviously modifications of the form or structure may be made withoutdeparting from the spirit or scope of the invention.

I claim:

1. A piano tuning device adapted to turn in either direction any one ofthe tuning pins of the pin block of a piano, comprising a socket wrenchadapted to engage axially the pin to be turned, a sleeve adapted to befitted over a second pin remote from the pin to be turned, said sleevehaving a reduced opening in the base thereof the wall of which openingis engageable with the pin at a point distant from the tip of the pin, alinkage having one end pivoted to said wrench and having the other endthereof pivoted to said sleeve, an internally toothed sector gearcoaxial and rigid with said wrench, a means for turning said sectorgear, said sleeve having an external flange on its base extendingoutwardly from the sleeve and a limit stop longitudinally spaced fromthe flange, a compression spring surrounding said sleeve between saidflange and said stop, said other end of said linkage being additionallyslidable on said sleeve and positioned between said spring and said stopwhence said spring normally urges said other end of the linkage outwardtoward said stop.

2. A piano tuning device adapted to turn in either direction any one ofthe tuning pins of the pin block of a piano, comprising a socket wrenchadapted to engage axially the pin to be turned, a sleeve adapted to befitted over a second pin remote from the pin to be turned, said sleevehaving a reduced opening in the base thereof the wall of which openingis engageable with the pin at a point distant from the tip of the pin, alinkage having one end pivoted to said wrench and having the other endthereof pivoted to said sleeve, an internally toothed sector gearcoaxial and rigid with said wrench, and means for turning said sectorgear, said linkage comprising an elongated arm extending from said oneend thereof and a link extending from said other end thereof, said armand said link having their juxtaposed ends pivoted together, said sleevehaving an external flange on its base and a limit stop longitudinallyspaced therefrom, a compression spring surrounding said sleeve betweensaid flange and said step, said other end of said linkage and hence ofsaid link being additionally slidable on said sleeve and positionedbetween said spring and said stop whence said spring normally urges saidlink outward toward said stop.

3. A piano tuning device adapted to turn in either direction any one ofthe tuning pins of the pin block of a piano, comprising a socket wrenchadapted to engage axially the pin to be turned, a sleeve adapted to befitted over a second pin remote from the pin to be turned, said sleevehaving a reduced opening in the base thereof the wall of which openingis engageable with the pin at a point distant from the tip of the pin, alinkage having one end pivoted to said wrench and having the other endthereof pivoted to said sleeve, an internally toothed sector gearcoaxial and rigid with said wrench, and means for turning said sectorgear, said sleeve having an external flange at its base and a limit stoplongitudinally spaced therefrom, a compression spring surrounding saidsleeve between said flange and said stop, said other end. of saidlinkage being additionally slidable on said sleeve and positionedbetween said spring and said stop whence said spring normally urges saidother end of the linkage outward toward said stop, said means comprisinga pinion rotatably mounted on that end link of the linkage which ispivotally attached to said wrench, said pinion being in mesh with saidinternally toothed sector gear, and means for rotating said pinion.

References Cited in the file of this patent UNITED STATES PATENTS

